Part of prison complex (8)
I believe the answer is:
compound
'complex' is the definition.
(associated in meaning)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for compound that I've seen before include "Whole formed by separate elements" , "See 10" , "In this fracture, bone has pierced the skin" , "A mix of ingredients" , "POW camp" .)